JP7418902B2 - Biodegradable super absorbent resin and its manufacturing method - Google Patents

Description

The present invention relates to a biodegradable superabsorbent resin that exhibits excellent biodegradability without deteriorating the physical properties of the superabsorbent resin, such as water retention capacity and pressurized water absorption capacity, and a method for producing the same.

Super Absorbent Polymer (SAP) is a synthetic polymer substance that has the ability to absorb 500 to 1,000 times its own weight in water. ) and AGM (Absorbent Gel Material). The above-mentioned superabsorbent resin has begun to be put into practical use as sanitary products, and is now used in addition to sanitary products such as disposable diapers for children, as well as soil repair agents for gardening, water-stopping materials for civil engineering and construction, sheets for growing seedlings, and freshness preservation in the food distribution field. It is widely used in applications such as cleaning agents, cleaning materials, and electrical insulation.

Such super absorbent resins are usually produced by bulk polymerization or suspension polymerization of acrylic acid monomers together with a crosslinking agent in the presence of a polymerization initiator to form a hydrogel polymer. Manufactured after obtaining. Therefore, most of the conventional superabsorbent resins are not biodegradable and cause environmental problems when disposed of as waste. Specifically, when various products to which superabsorbent resins are applied are disposed of in landfills, such superabsorbent resins are not decomposed by bacteria and microorganisms in the soil, which can cause environmental pollution.

Therefore, attempts have been made to create a superabsorbent resin that exhibits excellent biodegradability using biomass-derived materials, but it has not been possible to produce it economically while exhibiting various physical properties at a similar level to conventional superabsorbent resins. It has not been so easy to produce possible biodegradable superabsorbent resins.

As a result, there is a continuing demand for the development of superabsorbent resin-related technologies that can exhibit biodegradability without degrading the basic physical properties of the superabsorbent resin.

Therefore, the present invention provides a superabsorbent resin that exhibits excellent biodegradability without deterioration of the physical properties of the superabsorbent resin, such as water retention capacity and pressurized water absorption capacity, and a method for producing the same.

According to one embodiment of the invention:
Containing a crosslinked polymer of a monomer and an internal crosslinking agent containing a modified polysaccharide (polysaccharide) having a maleic acid group (-OCOCH=CHCOOH) and a sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH),
At least a portion of the maleic acid group and the sulfosuccinic acid group are neutralized,
The degree of maleic acid group substitution within the modified polysaccharide is 0.15 to 0.65,
The degree of substitution of sulfosuccinic acid groups within the modified polysaccharide is 0.05 to 0.60,
A biodegradable superabsorbent resin is provided.

According to yet another embodiment of the present invention, maleic acid groups (-OCOCH=CHCOOH) and sulfosuccinic acid groups (-OCOCH(SO ₃ H) CH ₂ COOH) are combined in the presence of an internal crosslinking agent and a polymerization initiator. producing a monomer composition comprising a modified polysaccharide having;
crosslinking and polymerizing the monomer composition to produce a hydrogel polymer; and drying, pulverizing, and classifying the hydrogel polymer.
In the method for producing biodegradable superabsorbent resin,
At least a portion of the maleic acid groups and sulfosuccinic acid groups of the modified polysaccharide are neutralized,
The degree of maleic acid group substitution within the modified polysaccharide is 0.15 to 0.65,
The degree of substitution of sulfosuccinic acid groups within the modified polysaccharide is 0.05 to 0.60,
A method for producing a biodegradable superabsorbent resin is provided.

Furthermore, according to another embodiment of the present invention, a sanitary product containing the biodegradable superabsorbent resin is provided.

The biodegradable superabsorbent resin of the present invention uses chemically modified modified polysaccharide and exhibits excellent biodegradability. In addition, the biodegradable superabsorbent resin of the present invention can be polymerized and crosslinked without unreacted modified polysaccharide by using a modified polysaccharide having a weight average molecular weight above a certain level, and has a high water retention capacity. Various physical properties of general super absorbent resins, such as pressure water absorption capacity, do not deteriorate. Therefore, even if the biodegradable superabsorbent resin is applied to various sanitary products, it will not cause environmental pollution when disposed of.

1 shows a ¹ H NMR spectrum of maleated chitosan prepared in Step 1 of Preparation Example 1. 1 shows a ¹ H NMR spectrum of the modified chitosan (M/S) finally produced in Production Example 1.

The terminology used herein is merely used to describe exemplary embodiments and is not intended to limit the invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. As used herein, terms such as "comprising," "comprising," or "having" are intended to specify the presence of implemented features, steps, components, or combinations thereof; It should be understood that this does not exclude in advance the existence or possibility of adding other features, steps, components, or combinations thereof.

In addition, in the present invention, when a layer or element is referred to as being formed "on" or "over" a layer or element, it means that the layer or element is formed directly on the layer or element. or other layers or elements may be additionally formed between each layer, on the object, or on the substrate.

Although the present invention is susceptible to various modifications and may take various forms, specific embodiments thereof will be exemplified and described in detail below. However, this is not intended to limit the invention to the particular disclosed form, but should be understood to include all modifications, equivalents, and alternatives that fall within the spirit and technical scope of the invention.

Additionally, the terminology used herein is merely to refer to particular embodiments and is not intended to limit the invention. As used herein, the singular form also includes the plural form unless the phrase clearly indicates the contrary.

On the other hand, the term "(meth)acrylate" used herein includes both acrylates and methacrylates.

The term "polymer" or "macromolecule" as used in the specification of the present invention means a polymerized state of a water-soluble ethylenically unsaturated monomer, and includes all water content ranges or particle size ranges. can be encompassed. Among the above polymers, a polymer in a state after polymerization and before drying and having a water content (moisture content) of about 40% by weight or more can be referred to as a hydrogel polymer. The ground and dried particles can be referred to as crosslinked polymers.

In addition, the term "super absorbent resin particles" refers to crosslinked polymers containing acidic groups, acidic groups and vinyl groups, which are obtained by polymerizing modified starch in which at least a portion of the acidic groups have been neutralized and crosslinked by an internal crosslinking agent. Refers to particulate matter, including coalescence.

Also, depending on the context, the term "super absorbent resin" refers to a crosslinked polymer having an acidic group and a vinyl group, in which a modified starch in which at least a portion of the acidic group has been neutralized is polymerized together with an internal crosslinking agent, or a crosslinked polymer having the above-mentioned crosslinked It refers to a base resin in the form of a powder consisting of super absorbent resin particles in which a polymer is pulverized, or the crosslinked polymer or base resin is subjected to additional steps, such as surface crosslinking or fine powder reassembly. It is used to encompass all products that have undergone processes such as , drying, pulverization, and classification to make them suitable for production.

Conventionally used super absorbent resins are produced by polymerizing acrylic acid monomers together with a crosslinking agent in the presence of a polymerization initiator, and super absorbent resins produced in this way are biodegradable. This is causing environmental problems.

Therefore, efforts have been made to develop superabsorbent resins that can exhibit biodegradability. Materials such as polysaccharide, polyaspartic acid, and polyglutamic acid are said to be biodegradable materials that can be used to produce such biodegradable resins. It has been difficult to replace superabsorbent resins produced from acrylic acid monomers by reducing the absorption capacity, which is an important physical property of water-absorbent resins.

Therefore, the present inventors created a super absorbent resin by using a modified polysaccharide (polysaccharide) having a maleic acid group (-OCOCH=CHCOOH) and a sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH) as a monomer. When manufacturing, it is important to note that general superabsorbent resins have not only excellent biodegradability but also various physical properties such as water retention capacity and pressurized water absorption capacity, which are superior to other known biodegradable materials. After confirming this, the present invention was completed.

Hereinafter, a biodegradable superabsorbent resin and a method for producing the same will be explained in more detail according to specific embodiments of the invention.

Biodegradable super absorbent resin Specifically, the biodegradable super absorbent resin according to one embodiment of the invention has a maleic acid group (-OCOCH=CHCOOH) and a sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH). It includes a crosslinked polymer of a monomer and an internal crosslinker, including a modified polysaccharide with a polysaccharide.

Here, the crosslinked polymer is a monomer containing a modified polysaccharide having at least a partially neutralized maleic acid group (-OCOCH=CHCOOH) and a sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH). The body is cross-linked and polymerized in the presence of an internal cross-linking agent, and has a three-dimensional network structure in which the main chain formed by polymerizing the polysaccharide is cross-linked by the internal cross-linking agent. In this way, when the crosslinked polymer has a three-dimensional network structure in which the main chain formed by polymerizing the polysaccharide is crosslinked by the internal crosslinking agent, 2 Compared to the case where the superabsorbent resin has a dimensional linear structure, the various physical properties of the superabsorbent resin, such as water retention capacity and pressurized water absorption capacity, can be significantly improved.

On the other hand, polysaccharide, that is, polysaccharide, refers to a polymeric carbohydrate molecule consisting of glucose repeating units, in which the hydroxyl group bonded to the 2nd carbon atom in the glucose repeating unit Glucosamine repeating unit with an amino group introduced and/or N-acetylglucosamine repeating unit with an N-acetylamino group introduced into the hydroxyl group bonded to the 2nd carbon atom in the glucose repeating unit It also includes polymer molecules consisting of acetylglucosamine units. Therefore, all compounds commonly known as polysaccharides can be used as the polysaccharide. Examples include, but are not limited to, starch consisting of glucose repeating units, chitosan consisting of glucosamine repeating units and N-acetylglucosamine repeating units, and the like.

Furthermore, the modified polysaccharide (modified polysaccharide) used in the biodegradable superabsorbent resin is a concept that is distinguished from the unmodified polysaccharide that is normally obtained naturally or synthetically. It means a compound in which the hydroxy group (-OH) in the glucose repeating unit of the polysaccharide has been replaced with another functional group by chemical treatment and/or heat treatment. Such modified polysaccharides can exhibit physical properties different from unmodified polysaccharides due to the functional group introduced in place of the hydroxyl group (-OH).

For example, the modified polysaccharide is modified starch or modified chitosan.

On the other hand, in the modified polysaccharide, a maleic acid group (-OCOCH=CHCOOH) and a sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH) are substituted, and the maleic acid group (-OCOCH=CHCOOH) and at least a portion of the sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH) is neutralized.

Furthermore, the maleic acid group (-OCOCH=CHCOOH) and the sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH) are attached to the 6th carbon of the glucose/glucosamine/N-acetylglucosamine repeating unit in the polysaccharide. It may be introduced into a hydroxy group. This is because the hydroxyl group bonded to the 6th carbon has better reactivity than the hydroxyl groups bonded to the 2nd and 3rd carbons. Here, the hydroxy group at carbon number 6 means a hydroxy group bonded to carbon number 6 when the glucose repeating unit of a general polysaccharide is represented by the following chemical formula A.

Further, the maleic acid group (-OCOCH=CHCOOH) in the polysaccharide may be introduced by maleic acid or maleic acid anhydride. For example, maleic anhydride can replace the hydroxyl group (-OH) present in the unmodified polysaccharide molecule with a maleic acid group (-OCOCH=CHCOOH).

At this time, the degree of substitution (DS) of the maleic acid group (-OCOCH=CHCOOH) of the modified polysaccharide is hereinafter expressed as "DS _M " and is 0.15 to 0.65. If the degree of substitution of the maleic acid group is less than 0.15, a large amount of modified polysaccharide that does not participate in crosslinking polymerization may remain; if the degree of substitution of the maleic acid group is more than 0.65, maleic A large amount of maleic anhydride used for introducing acid groups may not be completely removed, which may affect the physical properties of the final superabsorbent resin. Preferably, the degree of substitution of the maleic acid group is 0.16 or more, 0.17 or more, 0.18 or more, 0.19 or more, 0.20 or more, 0.21 or more, 0.22 or more, 0.23 or more. , 0.24 or more, 0.25 or more, 0.26 or more, 0.27 or more, 0.28 or more, 0.29 or more, 0.30 or more, 0.31 or more, 0.32 or more, 0.33 or more , 0.34 or more, 0.35 or more, or 0.36 or more; 0.64 or less, 0.63 or less, 0.62 or less, 0.61 or less, 0.60 or less, 0.59 or less, 0 .58 or less, 0.57 or less, 0.56 or less, 0.55 or less, 0.54 or less, 0.53 or less, 0.52 or less, or 0.51 or less.

Here, the degree of substitution of maleic acid groups means the average number of hydroxy groups (-OH) substituted with maleic acid groups per glucose repeating unit. That is, since there are three hydroxy groups per glucose repeat unit, the theoretical maximum degree of substitution is 3, and a degree of substitution of 0.1 means that one hydroxy group per 10 glucose repeat units is substituted. means that it has been done. The degree of substitution of the maleic acid group can be calculated through ¹ H NMR analysis of the finally produced modified polysaccharide, and for more specific details, refer to the below-mentioned production example.

Further, the sulfonic acid group in the polysaccharide is selected from the group consisting of sodium bisulfite, potassium bisulfite, ammonium sulfite, and sodium sulfite. It may also be introduced by one or more sulfite compounds. For example, the sulfonic acid groups can be introduced using sodium bisulfite.

Preferably, the sulfonic acid group may be introduced in the form of a sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH). In other words, the sulfonic acid group can be introduced into the form of a sulfosuccinic acid group by reacting the double bond of the previously introduced maleic acid group with the sulfite-based compound.

The degree of substitution of the sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH) of the modified polysaccharide is hereinafter expressed as "DS _S " and is 0.05 to 0.60. If the degree of substitution of the sulfosuccinic acid group is less than 0.05, there may be a limit to the improvement of water retention capacity and effective absorption capacity, and if the degree of substitution of the sulfosuccinic acid group is more than 0.60, it may not participate in polymerization. As a result, the number of vinyl groups reduced may make it difficult to secure a three-dimensional crosslinked polymer structure. Preferably, the degree of substitution of the sulfosuccinic acid group is 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.10 or more, 0.11 or more, 0.12 or more, 0.13. or more, 0.14 or more, 0.15 or more, or 0.16 or more; 0.59 or less, 0.58 or less, 0.57 or less, 0.56 or less, 0.55 or less, 0.54 or less; 0.53 or less, 0.52 or less, 0.51 or less, 0.50 or less, 0.49 or less, 0.48 or less, 0.47 or less, 0.46 or less, 0.45 or less, 0.44 or less, 0.43 or less, 0.42 or less, 0.41 or less, 0.40 or less, 0.39 or less, 0.38 or less, 0.37 or less, 0.36 or less, 0.35 or less, 0.34 or less, It is 0.33 or less, 0.32 or less, 0.31 or less, 0.30 or less, 0.29 or less, or 0.28 or less.

Preferably, the sum of the degree of substitution of the maleic acid group and the degree of substitution of the sulfosuccinic acid group (DS _M +DS _S ) is 1 or less, more preferably 0.2 or more, 0.3 or more, 0.4 or more, or 0.5 or more; 0.90 or less, 0.85 or less, 0.80 or less, 0.75 or less, or 0.70 or less.

Preferably, the ratio of the degree of substitution of the maleic acid group and the degree of substitution of the sulfosuccinic acid group in the modified polysaccharide (DS _S :DS _M ) is 1:0.1 to 1:3.0, more preferably 1. : 0.2 or more, or 1:0.3 or more; 1:2.5 or less, 1:2.4 or less, 1:2.3 or less, 1:2.2 or less, 1:2.1 or less , 1:2.0 or less, 1:1.9 or less, 1:1.8 or less, 1:1.7 or less, 1:1.6 or less, 1:1.5 or less, 1:1.4 or less, 1:1.3 or less, 1:1.2 or less, 1:1.1 or less, 1:1.0 or less, 1:0.9 or less, or 1:0.8 or less.

On the other hand, some of the maleic acid groups and sulfosuccinic acid groups of the modified polysaccharide are neutralized, and the degree of neutralization can be adjusted depending on the type of modified polysaccharide and the physical properties of the final superabsorbent resin to be achieved. For example, in the case of modified starch, its high molecular weight makes it insoluble in water or the degree of neutralization can be increased to neutralize the carboxyl group (COOH) to the carboxylate (COO-) form to increase its solubility in water. Specifically, the degree of neutralization of the modified polysaccharide may be 40 to 95 mol%, 40 to 80 mol%, or 45 to 75 mol%.

In one embodiment, the modified polysaccharide includes one or more repeating units represented by the following chemical formulas 1-1 to 1-3; and repeating units represented by the following chemical formulas 2-1 to 2-3. One or more of these can be included.

In the above chemical formulas 1-1 to 1-3 and 2-1 to 2-3,
Each M is independently hydrogen or an alkali metal.

Specifically, in the chemical formulas 1-1 to 1-3 and 2-1 to 2-3, M ⁺ is each independently H ⁺ , Na ⁺ , or K ⁺ .

For example, when the modified polysaccharide is modified starch or modified dextrin, it may contain repeating units represented by the chemical formulas 1-1 and 2-1, and when it is modified chitosan, it may contain repeating units represented by the chemical formulas 1-1 and 2-1. -2, repeating units represented by chemical formulas 1-3, 2-1 and 2-2.

In addition, the modified polysaccharide has a weight average molecular weight of 500 to 1,000,000 g/mol, and if the weight average molecular weight of the modified starch is too low, sufficient crosslinking will not occur and a large amount of unreacted modified starch will remain. If the weight average molecular weight is too high, the acid treatment and functional group introduction itself may be difficult due to the entanglement phenomenon of the polymer chains of the high molecular weight modified polysaccharide. There is a problem in that it is not easy to produce a modified polysaccharide having a weight exceeding 1,000,000 g/mol.

Here, the weight average molecular weight (Mw) can be measured using gel permeation chromatography (GPC) using polystyrene (PS) as a standard sample for calibration. More specifically, 200 mg of modified polysaccharide was diluted in 200 ml Dimethylformamide (DMF) solvent to prepare a sample of about 1000 ppm, and then passed through an RI detector at 1 ml/min flow using an Agilent 1200 series GPC instrument. Weight average molecular weight can be measured. At this time, the molecular weight of the sample can be calculated based on a calibration curve created using eight standard PS standards.

On the other hand, the modified polysaccharide may be modified starch. The modified starch may include amylose and amylopectin in a weight ratio of 1:99 to 50:50 based on the total weight. The above-mentioned modification in which the hydroxyl group bonded to the 6th carbon of the glucose repeating unit is replaced with another substituent can occur for both amylose and amylopectin, but the content of amylopectin is It is advantageous if the amylose content is greater than or equal to the amylose content.

Further, the modified starch may have a gelatinization temperature of 50 to 90° C. and a peak viscosity (BU) of 50 to 1,000.

The modified starch may be a modified starch of one or more of potato starch, corn starch, rice starch, wheat starch, tapioca starch, and sweet potato starch. In particular, potato starch with a high content of amylopectin is preferred from the viewpoint of processability and solubility.

Meanwhile, the monomer may further include an acrylic acid compound having at least a partially neutralized acidic group.

The acrylic acid monomer is a compound represented by the following chemical formula 3:

[Chemical formula 3]
R-COOM'

In the chemical formula 3 above,
R is an alkyl group having 2 to 5 carbon atoms containing an unsaturated bond,
M' is a hydrogen atom, a monovalent or divalent metal, an ammonium group, or an organic amine salt.

Preferably, the monomer is one or more selected from the group consisting of (meth)acrylic acid, and monovalent (alkali) metal salts, divalent metal salts, ammonium salts, and organic amine salts of these acids. You can.

When (meth)acrylic acid and/or its salt is used as the acrylic acid monomer in this manner, it is advantageous that a super absorbent resin with improved water absorption can be obtained.

Here, the acrylic acid monomer may have an acidic group, and at least a portion of the acidic group may be neutralized. Preferably, the monomers partially neutralized with an alkaline substance such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc. can be used. At this time, the degree of neutralization of the acrylic acid monomer may be 40 to 95 mol%, 40 to 80 mol%, or 45 to 75 mol%. The range of the degree of neutralization can be adjusted depending on the final physical properties. However, if the degree of neutralization is too high, neutralized monomers may precipitate, making it difficult for polymerization to proceed smoothly; conversely, if the degree of neutralization is too low, the absorbency of the polymer may be reduced. Not only is it significantly reduced, but it may also exhibit elastic rubber-like properties that are difficult to handle.

In addition, the term "internal crosslinking agent" used in this specification is a term used to distinguish it from a surface crosslinking agent that is normally used to crosslink the surface of superabsorbent resin particles, and is It plays a role in crosslinking and polymerizing the vinyl groups of saccharides. Although the crosslinking in the above step is carried out without any separation on the surface or inside, when the surface crosslinking process of the superabsorbent resin particles is performed, the particle surface of the final produced superabsorbent resin is crosslinked with a surface crosslinking agent. The internal structure is crosslinked by the internal crosslinking agent.

As the internal crosslinking agent, any compound can be used as long as it enables the introduction of crosslinking bonds during polymerization of the modified polysaccharide. As non-limiting examples, the internal crosslinking agents include N,N'-methylenebisacrylamide, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol(meth)acrylate, polyethylene glycol di( meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol (meth)acrylate, butanediol di(meth)acrylate, butylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, Triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, dipentaerythritol pentaacrylate, glycerin tri(meth)acrylate, pentaerythol tetraacrylate, triarylamine, Polyfunctional crosslinking agents such as ethylene glycol diglycidyl ether, propylene glycol, glycerin, or ethylene carbonate may be used alone or in combination of two or more, but are not limited thereto. Of these, N,N'-methylenebisacrylamide or polyethylene glycol diacrylate can be preferably used.

The crosslinking polymerization of the modified starch in the presence of such an internal crosslinking agent is carried out by thermal polymerization in the presence of a polymerization initiator, optionally a thickener, a plasticizer, a storage stabilizer, an antioxidant, etc. The polymerization may be carried out by photopolymerization or hybrid polymerization, the details of which will be described later.

Further, the superabsorbent resin may be in the form of particles having an average particle size of 150 to 850 μm. At this time, the particle size can be measured by the European Disposables and Nonwovens Association (EDANA) standard EDANA WSP 220.3 method. More specifically, the super absorbent resin composition comprises super absorbent resin particles in which about 90% by weight, preferably 95% by weight or more based on the total weight, have a particle size of about 150 to 850 μm. Also, less than about 10% by weight, and more specifically less than about 5% by weight, may be fine powder having a particle size less than about 150 μm. When the superabsorbent resin contains a large amount of fine powder having a particle size of less than 150 μm, it is not preferable because various physical properties of the superabsorbent resin may be deteriorated.

Further, the biodegradable superabsorbent resin may have a water retention capacity (CRC) of 10 to 50 g/g as measured by EDANA method WSP 241.3.

Further, the biodegradable superabsorbent resin may have a water absorption capacity under pressure (AUP) of 5 to 30 g/g at 0.7 psi as measured by EDANA method WSP 242.3.

Method for producing biodegradable super-absorbent resin On the other hand, the biodegradable super-absorbent resin can be produced by the following production method:
Monomers containing modified polysaccharides with maleic acid groups (-OCOCH=CHCOOH) and sulfosuccinic acid groups (-OCOCH(SO ₃ H) CH ₂ COOH) in the presence of internal crosslinking agents and polymerization initiators. manufacturing the composition;
crosslinking and polymerizing the monomer composition to produce a hydrogel polymer; and drying, pulverizing, and classifying the hydrogel polymer.
In the method for producing biodegradable superabsorbent resin,
At least a portion of the maleic acid groups and sulfosuccinic acid groups of the modified polysaccharide are neutralized,
The degree of maleic acid group substitution within the modified polysaccharide is 0.15 to 0.65,
The degree of substitution of sulfosuccinic acid groups within the modified polysaccharide is 0.05 to 0.60,
Method for producing biodegradable super absorbent resin.

On the other hand, the modified polysaccharide is
A first step of acid treatment of unmodified polysaccharide;
a second step of reacting the acid-treated polysaccharide produced in the first step with maleic acid or maleic acid anhydride; and a polysaccharide produced in the second step. can be produced by including a third step of reacting with a sulfite-based compound.

First, as a first step for producing a modified polysaccharide, a non-modified polysaccharide can be treated with an acid. Such acid treatment destroys the rigid structure of starch due to hydrogen bonding and allows modification of polysaccharides such as maleation in the second step and sulfonation in the third step, which will be described later. This is done to increase manufacturing efficiency. Specifically, the acid treatment may be performed using an acidic solution such as hydrochloric acid at a temperature of 25 to 50° C. for 6 to 48 hours.

Next, the polysaccharide treated with acid in the first step is reacted with maleic acid or maleic acid anhydride to produce a polysaccharide into which maleic acid groups have been introduced. A second step can be performed. In addition, the reaction between the acid-treated polysaccharide and maleic acid or maleic acid anhydride in the second step may be performed at a temperature of 50 to 100° C. for 4 to 12 hours. .

As an example, the acid-treated polysaccharide can be subjected to maleation using maleic anhydride, thereby producing a polysaccharide substituted with maleic acid groups.

Next, the polysaccharide produced in the second step may be reacted with a sulfite-based compound to produce a polysaccharide in which a sulfonic acid group is additionally introduced in addition to carboxyl groups and vinyl groups. At this time, the sulfite compound is one selected from the group consisting of sodium bisulfite, potassium bisulfite, ammonium sulfite, and sodium sulfite. The above compounds can be used. Further, specifically, the reaction between the polysaccharide produced in the second step of the third step and the sulfite compound can be carried out at a temperature of 30 to 60° C. for 4 to 12 hours.

Furthermore, the sulfite compound can react with the vinyl group introduced into the polysaccharide.

As an example, the sulfite-based compound can be used to sulfonate the maleic acid group in the polysaccharide, in other words, the polysaccharide in which the maleic acid group has been substituted can be sulfosuccinylated, whereby the maleic acid group can be sulfosuccinylated. Polysaccharides substituted with acid groups and sulfosuccinic acid groups can be produced.

Next, the modified starch prepared above may be crosslinked and polymerized in the presence of an internal crosslinking agent and a polymerization initiator to form a hydrogel polymer.

The steps include preparing a monomer composition by mixing the modified starch, an internal crosslinking agent, and a polymerization initiator, and thermally or photopolymerizing the monomer composition to form a hydrogel polymer. It may consist of the steps of At this time, the description regarding the modified starch and the internal crosslinking agent is referred to above.

Additionally, the monomer composition may further include an acrylic acid-based compound having at least a partially neutralized acidic group. The modified polysaccharide and the acrylic acid compound may be included in the monomer composition in a weight ratio of 99:1 to 1:99. When the above-mentioned range is satisfied, the biodegradable superabsorbent resin can exhibit excellent biodegradability and at the same time improve water absorbency and water retention capacity.

In the monomer composition, the internal crosslinking agent may be used in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the modified polysaccharide. For example, the amount of the internal crosslinking agent is 0.1 parts by weight or more, or 0.2 parts by weight or more, and 5 parts by weight or less, 3 parts by weight or less, 1 part by weight or less, based on 100 parts by weight of the modified polysaccharide. It can be used in an amount of not more than 0.5 part by weight or less than 0.5 part by weight. If the content of the internal crosslinking agent is too low, crosslinking may not occur sufficiently and it may be difficult to achieve a strength above an appropriate level. If the content of the internal crosslinking agent is excessively high, the internal crosslinking density will increase to the desired level. It may be difficult to achieve this water retention capacity.

In addition, the polymerization initiator can be appropriately selected depending on the polymerization method; a thermal polymerization initiator is used when a thermal polymerization method is used, a photopolymerization initiator is used when a photopolymerization method is used, and a photopolymerization initiator is used when a hybrid polymerization method is used. (method using both heat and light), both a thermal polymerization initiator and a photopolymerization initiator can be used. However, depending on the photopolymerization method, a certain amount of heat is generated by light irradiation such as ultraviolet irradiation, and a certain amount of heat is also generated by the progress of the polymerization reaction, which is an exothermic reaction, so it is necessary to additionally use a thermal polymerization initiator. You can also use

The photopolymerization initiator can be used without any limitation in composition as long as it is a compound that can form radicals when exposed to light such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin ether, dialkyl acetophenone, hydroxyl alkyl ketone, phenyl glyoxylate, and benzyl dimethyl ketone. Tar (Benzyl Dimethyl Ketal), One or more selected from the group consisting of acyl phosphine and alpha-aminoketone can be used. On the other hand, specific examples of acylphosphines include diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and ethyl(2,4,6-trimethylbenzoyl) Examples include phenylphosphinate. For more diverse light starting agents, "UV Coatings: BASICS: BASICS, RECENT Developments and New APPLICATION (ELSEVIER 2007)" P115 , Not limited to the above example.

Further, as the thermal polymerization initiator, one or more selected from the initiator group consisting of persulfate-based initiators, azo-based initiators, hydrogen peroxide, and ascorbic acid can be used. Specifically, examples of persulfate-based initiators include sodium persulfate (Na ₂ S ₂ O ₈ ), potassium persulfate (K ₂ S ₂ O ₈ ), and ammonium persulfate (Ammonium persulfate). (NH ₄ ) ₂ S ₂ O ₈ ), and examples of azo initiators include 2,2-azobis(2-amidinopropane) dihydrochloride (2,2-azobis(2-amidinopropane) ) dihydrochloride), 2,2-azobis-(N,N-dimethylene)isobutyramidine dihydrochloride trill (2-(carbamoylazo)isobutylonitril), 2,2-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (2,2-azobis[2-(2-imidazolin-2-yl)propane ] dihydrochloride), 4,4-azobis-(4-cyanovaleric acid), and the like. A more variety of thermal polymerization initiators are well described in "Principle of Polymerization" by Odian (Wiley, 1981), p. 203, and are not limited to the above-mentioned examples.

Such a polymerization initiator can be used in an amount of 2 parts by weight or less based on 100 parts by weight of the modified polysaccharide. That is, if the concentration of the polymerization initiator is too low, the polymerization rate will be slow and a large amount of residual monomer may be extracted into the final product, which is not preferable. On the other hand, if the concentration of the polymerization initiator is higher than the above range, the polymer chains forming the network will become shorter, the content of water-soluble components will increase, and the physical properties of the resin will deteriorate, such as a decrease in water absorption capacity under pressure. I don't like it.

The monomer composition may further include additives such as a thickener, a plasticizer, a storage stabilizer, and an antioxidant, if necessary.

When the monomer composition containing the monomer is insoluble like high molecular weight starch, it may be in a suspension state, and when it is water soluble like low molecular weight dextrin, It may be in a solution state dissolved in a solvent such as water. The solid content in such a monomer composition, that is, the concentration of the monomer, internal crosslinking agent, and polymerization initiator, can be appropriately adjusted in consideration of the polymerization time, reaction conditions, and the like. For example, the solids content within the monomer composition may be 10-80%, or 15-60%, or 30-50% by weight.

When the monomer composition has a solids content in the above range, the gel effect phenomenon that appears in the polymerization reaction of a highly concentrated aqueous solution can be used to eliminate the need to remove unreacted monomers after polymerization. may also be advantageous for adjusting the grinding efficiency during grinding of the polymers described below.

Solvents that can be used at this time can be used without any limitation as long as they can dissolve the above-mentioned components, and examples include water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, propylene glycol, and ethylene glycol. Monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol ethyl ether, toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate and N , N-dimethylacetamide and the like can be used in combination.

On the other hand, the crosslinking polymerization of the modified polysaccharide can be carried out without particular configuration limitations, as long as a hydrogel polymer can be formed by thermal polymerization, photopolymerization, or hybrid polymerization.

Specifically, polymerization methods are broadly divided into thermal polymerization and photopolymerization depending on the polymerization energy source, and when thermal polymerization is normally performed, it can be performed in a reactor with a stirring shaft such as a kneader, and photopolymerization is performed. In this case, it can be carried out in a reactor equipped with a movable conveyor belt or in a flat-bottomed vessel, but the above-mentioned polymerization method is only an example, and the present invention is not limited to the above-mentioned polymerization method.

For example, as mentioned above, a hydrogel polymer obtained by thermal polymerization by supplying hot air or heating the reactor to a reactor such as a kneader equipped with a stirring shaft is placed in the reactor. Depending on the shape of the provided stirring shaft, the hydrogel polymer discharged into the reactor outlet may have a shape of several centimeters to several millimeters. Specifically, the size of the obtained hydrogel polymer varies depending on the concentration and injection speed of the monomer composition injected, and a hydrogel polymer having a weight average particle size of 2 to 50 mm is usually obtained. .

Furthermore, when photopolymerization is carried out in a reactor equipped with a movable conveyor belt or in a flat-bottomed container as described above, the form of the hydrogel polymer obtained is usually a sheet-like hydrogel polymer having the width of the belt. It may be. At this time, the thickness of the polymer sheet varies depending on the concentration of the monomer composition to be injected and the injection speed or injection amount, but usually a sheet-like polymer having a thickness of about 0.5 to about 5 cm is obtained. Preferably, the monomer composition is supplied to the monomer composition. If the monomer composition is supplied to the extent that the thickness of the sheet-shaped polymer is excessively thin, production efficiency will be low, which is undesirable, and if the thickness of the sheet-shaped polymer exceeds 5 cm, the thickness will be excessively large. Depending on the thickness, the polymerization reaction may not occur uniformly throughout the thickness.

At this time, the hydrogel polymer obtained by such a method may have a water content of 40 to 70% by weight. For example, the water content of the hydrogel polymer may be 40% by weight or more, 45% by weight or more, or 50% by weight or more, and 70% by weight or less, 65% by weight or less, or 60% by weight or less. If the water content of the hydrogel polymer is too low, it may be difficult to secure an appropriate surface area in the subsequent pulverization step, which may reduce drying efficiency, and if the water content of the hydrogel polymer is too high, The pressure applied in the subsequent pulverization step may increase and the water absorption capacity under pressure may decrease, and the drying step after pulverization may require a lot of energy and a long time.

On the other hand, throughout this specification, "water content" refers to the content of water relative to the total weight of the hydrogel polymer, and means the value obtained by subtracting the weight of the dry polymer from the weight of the hydrogel polymer. do. Specifically, it is defined as a value calculated by measuring the weight loss due to water evaporation in the polymer during the process of raising the temperature of the polymer in crumb state through infrared heating and drying it. At this time, drying for measuring the moisture content is performed by raising the temperature to about 50° C. at room temperature and then vacuum drying at 50° C. for about 6 hours.

Meanwhile, after the production of the hydrogel polymer, a coarse pulverization step of pulverizing the produced hydrogel polymer can be selectively performed prior to the subsequent drying and pulverization steps.

The coarse grinding process is a process for increasing the drying efficiency in the subsequent drying process and controlling the particle size of the super absorbent resin powder to be finally manufactured. Specific examples include, but are not limited to, a vertical pulverizer, a turbo cutter, a turbo grinder, a rotary cutter mill, and a cutter mill. ), Disc mill, Shred crusher, Crusher, meat chopper, and Disc cutter. However, it is not limited to the above example.

The coarse pulverization step can be performed, for example, so that the hydrogel polymer has a particle size of about 2 to about 10 mm. It is technically difficult to grind the hydrogel polymer to a particle size of less than 2 mm due to the high water content of the hydrogel polymer, and a phenomenon in which the pulverized particles agglomerate with each other occurs. There is also. On the other hand, when the particles are crushed to a particle size exceeding 10 mm, the effect of increasing the efficiency of the subsequent drying step is small.

Next, the step of drying, pulverizing, and classifying the hydrogel-like polymer produced in the above step to produce a base resin is performed.

The drying method can be selected and used without limitation as long as it is normally used as a drying process for hydrogel polymers. Specifically, the drying step can be performed by supplying hot air, infrared irradiation, ultrahigh frequency irradiation, ultraviolet irradiation, or the like.

Specifically, the drying can be carried out under vacuum conditions at a temperature below 100°C, specifically at a temperature of about 30°C to about 80°C. If the drying temperature is 100° C. or higher, the modified polysaccharide may be decomposed, making it unsuitable. If the drying temperature is lower than 30° C., the drying time may become excessively long.

On the other hand, the drying time may be approximately 20 to approximately 90 minutes in consideration of process efficiency, but is not limited thereto.

The water content of the polymer after such drying step may be from about 5 to about 10% by weight.

After the drying process, a pulverizing process is performed.

The grinding process may be performed such that the particle size of the polymer powder, ie, the base resin, is about 150 to about 850 μm. Mills used to grind to such particle sizes include pin mills, hammer mills, screw mills, roll mills, and disc mills. mill or jog mill, etc., but the invention is not limited to the above-mentioned example.

Further, after the above-mentioned pulverization step, the pulverized polymer powder may be further classified according to particle size in order to control the physical properties of the final product of the superabsorbent resin.

Preferably, a polymer having a particle size of about 150 to about 850 μm is classified, and only the polymer having such a particle size can be used as a base resin to be manufactured into a product through a surface crosslinking reaction step.

The base resin obtained as a result of the above process may have a powder form including a crosslinked polymer that is crosslinked using an acrylic acid monomer and an internal crosslinking agent. Specifically, the base resin may have a powder form with a particle size of 150 to 850 μm.

On the other hand, there is further provided a sanitary product containing the above-mentioned biodegradable superabsorbent resin.

Below, preferred embodiments are presented for understanding the invention. However, the following examples are merely for illustrating the invention and are not intended to limit the invention to these.

Production Example 1: Production of modified chitosan (M/S) (1) Step 1: Maleic oxidation step of chitosan 20 g of chitosan and 100 g of maleic anhydride were put into a 250 ml three-necked flask, and then heated at 90°C for 6 hours. Stir for hours. After the reaction, the mixture was precipitated into an acetone solvent and filtered to remove excess maleic anhydride, and dried at 50° C. for 24 hours or more to obtain maleated chitosan.

(2) Step 2: Step of sulfonation of at least a part of the maleated functional groups After putting 20 g of maleated chitosan and 5 g of sodium bisulfite into a 250 ml three-necked flask, the mixture was heated at 40°C. Stirred for 6 hours. After stirring, the reaction mixture was adjusted to pH 6-7 by adding Na ₂ CO ₃ , washed several times with water and ethanol, and dried at 50°C for over 24 hours to form the final maleic acid group (-OCOCH=CHCOOH). And modified chitosan (M/S) into which a sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH) group was introduced was produced.

The weight average molecular weight of the produced chitosan is 50,000 g/mol, the degree of substitution (DS M ) of the maleic acid group (-OCOCH=CHCOOH) is 0.22, and the degree of substitution (DS _M ) of the maleic acid group (-OCOCH=CHCOOH) is 0.22, and the degree of substitution (DS M ) of the maleic acid group (-OCOCH=CHCOOH) is _0.22 . H) CH ₂ COOH) degree of substitution (DS _S ) was 0.55. At this time, the degree of substitution of each of these substituents is calculated based on the integral ratio of the peak corresponding to vinyl (CH=CH, 6.3 ppm) of the maleic acid group in ¹ H NMR. However, the specific calculation method is as follows.

First, a ¹ H NMR spectrum of the maleated chitosan prepared in Step 1 was obtained and is shown in FIG. Referring to Figure 1, a peak appeared at 6.3 ppm, which corresponds to the vinyl group of the maleic acid group, confirming that the maleic acid group was introduced into chitosan. Based on the (Integral) ratio, the degree of maleic acid group (-OCOCH=CHCOOH) substitution of the maleated chitosan prepared in step 1 was determined.

Next, a ¹ H NMR spectrum was obtained for the finally produced modified chitosan (M/S), which is shown in FIG. Referring to Figure 2, since the peak at 6.3 ppm corresponding to the vinyl group of the maleic acid group decreased, the vinyl group of the maleic acid group decreased due to the introduction of a sulfonic acid group to the vinyl group of the maleic acid group. I was able to confirm that it was done. Furthermore, the degree of maleic acid group (-OCOCH=CHCOOH) substitution of the finally produced modified chitosan (M/S) was determined based on the integral ratio of the peaks. Furthermore, this allows calculation of the degree of substitution of the sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH) of the finally produced modified chitosan (M/S).

Production Example 2: Production of modified starch 1 (M/S-1) (1) Step 1: Acid treatment step of unmodified starch 20 g of starch was added to 200 ml of 2M HCl solution, and then stirred at 35° C. for 24 hours. Thereafter, it was filtered, washed several times with water and ethanol, and then dried at 50° C. for more than 24 hours to obtain acid-treated starch.

(2) Step 2: Maleation step of acid-treated starch 20 g of acid-treated starch and 100 g of maleic anhydride were put into a 250 ml three-necked flask and stirred at 90° C. for 6 hours. After the reaction, the mixture was precipitated in an acetone solvent and filtered to remove excess maleic anhydride, and dried at 50° C. for 24 hours or more to obtain maleated modified starch.

(3) Step 3: Step of sulfonation of at least some of the maleated functional groups After putting 20 g of maleated modified starch and 5 g of sodium bisulfite into a 250 ml three-necked flask, the mixture was heated at 40°C. The mixture was stirred for 6 hours. After stirring, the reaction mixture was adjusted to pH 6-7 by adding Na ₂ CO ₃ , washed several times with water and ethanol, and dried at 50°C for over 24 hours to form the final maleic acid group (-OCOCH=CHCOOH). And modified starch 1 (M/S-1) into which a sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH) group was introduced was produced.

The produced modified starch has a weight average molecular weight of 50,000 g/mol, a degree of substitution (DS _M ) of maleic acid groups (-OCOCH=CHCOOH) of 0.62, and a sulfosuccinic acid group (-OCOCH(SO _3H ) _CH2COOH ) degree of substitution ( _DSS ) was 0.07.

At this time, the degree of substitution of each substituent is determined by determining the ¹ H NMR spectra of the maleated modified starch produced in step 2 and the final modified starch (M/S), and then determining the degree of substitution for each substituent. It was calculated based on the integral ratio of the peak corresponding to vinyl maleic acid group (CH=CH, 6.3 ppm). For a specific calculation method, refer to the substitution degree calculation method for modified chitosan (M/S) in Production Example 1, and calculations were made in the same manner for the remaining production examples below.

Production Example 3: Production of Modified Starch 2 (M/S-2) Modified Starch 2 (M/S-2) was produced using the same method as Production Example 2, except that 10 g of sodium bisulfite was used in Production Example 2. /S-2) was produced.

The modified starch produced above has a weight average molecular weight of 50,000 g/mol, a degree of substitution (DS _M ) of maleic acid groups (-OCOCH=CHCOOH) of 0.51, and a sulfosuccinic acid group (-OCOCH(SO _3H ) _CH2COOH ) degree of substitution ( _DSS ) was 0.16.

Production Example 4: Production of Modified Starch 3 (M/S-3) Modified Starch 3 (M/S-3) was produced using the same method as Production Example 2, except that 14 g of sodium bisulfite was used in Production Example 2. /S-3) was produced.

The modified starch produced above has a weight average molecular weight of 50,000 g/mol, a degree of substitution (DS _M ) of maleic acid groups (-OCOCH=CHCOOH) of 0.36, and a sulfosuccinic acid group (-OCOCH(SO _3H ) _CH2COOH ) degree of substitution ( _DSS ) was 0.28.

Production Example 5: Production of Modified Starch 4 (M/S-4) Modified Starch 4 (M/S-4) was produced using the same method as Production Example 2, except that 20 g of sodium bisulfite was used in Production Example 2. /S-4) was produced.

The modified starch produced above has a weight average molecular weight of 50,000 g/mol, a degree of substitution (DS _M ) of maleic acid groups (-OCOCH=CHCOOH) of 0.21, and a sulfosuccinic acid group (-OCOCH(SO _3H ) _CH2COOH ) degree of substitution ( _DSS ) was 0.43.

Comparative Production Example 1: Production of modified starch (M) (1) Step 1: Acid treatment step of unmodified starch 20 g of starch was added to 200 ml of 2M HCl solution, and then stirred at 35° C. for 24 hours. Thereafter, it was filtered, washed several times with water and ethanol, and then dried at 50° C. for more than 24 hours to obtain acid-treated starch.

(2) Step 2: Maleation step of acid-treated starch 20 g of acid-treated starch and 100 g of maleic anhydride were put into a 250 ml three-necked flask and stirred at 90° C. for 6 hours. After the reaction, the mixture was precipitated in an acetone solvent and filtered to remove excess maleic anhydride, and dried at 50°C for 24 hours or more to obtain maleated modified starch (M). Ta.

The final produced modified starch (M) had a weight average molecular weight of 50,000 g/mol and a degree of substitution (DS _M ) of maleic acid groups (-OCOCH=CHCOOH) of 0.70.

Comparative Production Example 2: Production of modified starch (M/S') Modified starch (M/S') was produced using the same method as Production Example 2, except that 30 g of sodium bisulfite was used in Production Example 2. ') was manufactured.

The modified starch produced above has a weight average molecular weight of 50,000 g/mol, a degree of substitution (DS _M ) of maleic acid groups (-OCOCH=CHCOOH) of 0.14, and a sulfosuccinic acid group (-OCOCH(SO _3H ) _CH2COOH ) degree of substitution ( _DSS ) was 0.54.

Example 1
In a 3L glass container equipped with a stirrer, a nitrogen injector, and a thermometer, 100 g of the modified chitosan (M/S) produced in Production Example 1, 0.23 g of polyethylene glycol diacrylate (Mn = 575) as an internal crosslinking agent, and light Add 0.008 g of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide as an initiator, 0.12 g of sodium persulfate (SPS) as a thermal initiator, 39.7 g of 98% sodium hydroxide solution and 200 g of water. A monomer composition was produced while nitrogen was continuously introduced.

The monomer composition was added to a stainless steel container measuring 250 mm in width, 250 mm in length, and 30 mm in height, irradiated with ultraviolet rays for 60 seconds (irradiation amount: 10 mV/cm ² ) in a UV chamber at 80° C., and aged for 2 minutes ( aging) to obtain a hydrogel polymer.

After crushing the obtained hydrogel-like polymer into a size of 3 mm x 3 mm, the obtained gel-type resin was spread to a thickness of about 30 mm on stainless steel wire gauze having a pore size of 600 μm. It was dried in a vacuum oven at 10°C for 10 hours. The dry polymer thus obtained is pulverized using a pulverizer and classified using a standard mesh sieve according to ASTM standards to obtain a base resin having a particle size of 300 to 600 μm. Made of resin.

Examples 2 to 5
A superabsorbent resin was produced in the same manner as in Example 1, except that modified starch shown in Table 1 below was used instead of modified chitosan (M/S).

Comparative examples 1 and 2
A superabsorbent resin was produced in the same manner as in Example 1, except that modified starch shown in Table 1 below was used instead of modified chitosan (M/S).

Experimental Example The physical properties of the superabsorbent resins produced in the Examples and Comparative Examples were evaluated in the following manner, and the results are shown in Table 1 below.

Unless otherwise specified, all physical property evaluations below were performed at constant temperature and humidity (23±1° C., relative humidity 50±10%), and physiological saline or salt water refers to a 0.9% by weight sodium chloride (NaCl) aqueous solution.

(1) Centrifuge Retention Capacity (CRC)
The water retention capacity of each resin in terms of absorption capacity under no load was measured using EDANA WSP 241.3.

Specifically, super absorbent resin W ₀ (g) (approximately 0.2 g) was uniformly placed in a nonwoven envelope and sealed, and then immersed in physiological saline (0.9% by weight) at room temperature. I let it happen. After 30 minutes, the envelope was drained for 3 minutes using a centrifuge at 250 G, and the mass W ₂ (g) of the envelope was measured. Moreover, after performing the same operation without using the resin, the mass W ₁ (g) at that time was measured. CRC (g/g) was calculated using the following formula using each mass obtained.

[Formula 1]
CRC (g/g) = {[W ₂ (g) - W ₁ (g)]/W ₀ (g)} - 1

(2) Absorption Under Pressure (AUP)
The 0.7 psi pressurized water absorption capacity of each resin was determined by EDANA method WSP 242.3.

Specifically, a stainless steel 400 mesh iron mesh was attached to the bottom of a plastic cylinder with an inner diameter of 60 mm. Super absorbent resin W ₀ (g) (0.90 g) can be uniformly spread on the iron mesh under conditions of room temperature and 50% humidity, and a load of 0.7 psi can be further applied uniformly on it. The piston has an outer diameter slightly smaller than 60 mm and has no gap with the inner wall of the cylinder, so that its vertical movement is not hindered. At this time, the weight W ₃ (g) of the device was measured.

A glass filter with a diameter of 90 mm and a thickness of 5 mm was placed inside a Petri dish with a diameter of 150 mm, and physiological saline containing 0.9% by weight of sodium chloride was placed at the same level as the top surface of the glass filter. A sheet of filter paper with a diameter of 90 mm was placed on top of it. The measuring device was placed on the filter paper and the liquid was allowed to absorb under load for 1 hour. After 1 hour, the measuring device was lifted and its weight W ₄ (g) was measured.

Using the obtained masses, the pressurized water absorption capacity (g/g) was calculated using the following formula.

[Formula 2]
AUP (g/g) = [W ₄ (g) - W ₃ (g)] / W ₀ (g)

(3) Biodegradability test Measured based on KS M ISO 14855-1 standard.

Claims (10)

Containing a crosslinked polymer of a monomer and an internal crosslinking agent containing a modified polysaccharide (polysaccharide) having a maleic acid group (-OCOCH=CHCOOH) and a sulfosuccinic acid group (-OCOCH(SO ₃ H) CH ₂ COOH),
At least a portion of the maleic acid group and the sulfosuccinic acid group are neutralized,
The degree of maleic acid group substitution within the modified polysaccharide is 0.15 to 0.65,
The degree of substitution of sulfosuccinic acid groups in the modified polysaccharide is 0.05 to 0.60,
The monomer includes an acrylic acid compound having at least a partially neutralized acidic group .
Biodegradable super absorbent resin. The biodegradable superabsorbent resin according to claim 1, wherein the modified polysaccharide is modified starch or modified chitosan. The biodegradable superabsorbent resin according to claim 1 or 2, wherein the maleic acid group is introduced by maleic acid or maleic acid anhydride. The biodegradable superabsorbent resin according to any one of claims 1 to 3, wherein the total of the degree of substitution of the maleic acid group and the degree of substitution of the sulfosuccinic acid group is 1 or less. The biodegradable superabsorbent according to any one of claims 1 to 4, wherein the ratio of the degree of substitution of the maleic acid group and the degree of substitution of the sulfosuccinic acid group is 1:0.1 to 1:3.0. resin. The modified polysaccharide includes one or more repeating units represented by the following chemical formulas 1-1 to 1-3; and one or more repeating units represented by the following chemical formulas 2-1 to 2-3. The biodegradable superabsorbent resin according to any one of claims 1 to 5, comprising:
In the above chemical formulas 1-1 to 1-3 and 2-1 to 2-3,
Each M is independently hydrogen or an alkali metal. Monomers containing modified polysaccharides with maleic acid groups (-OCOCH=CHCOOH) and sulfosuccinic acid groups (-OCOCH(SO ₃ H) CH ₂ COOH) in the presence of internal crosslinking agents and polymerization initiators. manufacturing the composition;
crosslinking and polymerizing the monomer composition to produce a hydrogel polymer; and drying, pulverizing, and classifying the hydrogel polymer.
In the method for producing biodegradable superabsorbent resin,
At least a portion of the maleic acid groups and sulfosuccinic acid groups of the modified polysaccharide are neutralized,
The degree of maleic acid group substitution within the modified polysaccharide is 0.15 to 0.65,
The degree of substitution of sulfosuccinic acid groups in the modified polysaccharide is 0.05 to 0.60,
The monomer composition includes an acrylic acid compound having at least a partially neutralized acidic group .
Method for producing biodegradable super absorbent resin. The modified polysaccharide is
A first step of acid treatment of unmodified polysaccharide;
a second step of reacting the acid-treated polysaccharide produced in the first step with maleic acid or maleic acid anhydride; and a polysaccharide produced in the second step. The method for producing a biodegradable superabsorbent resin according to claim 7 , which includes a third step of reacting the biodegradable superabsorbent resin with a sulfite compound. In the third step,
The method for producing a biodegradable superabsorbent resin according to claim 8 , wherein the sulfite compound reacts with a vinyl group introduced into the polysaccharide. A sanitary product comprising the biodegradable superabsorbent resin according to any one of claims 1 to 6 .

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